Superregenerative limiter



Feb. 17, 1942. M. G. CROSBY SUPERREGENERATIVE LIMITER Filed Feb. 3, 19406 Sheets-Sheet l DNN www

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ATTORNEY Feb. 17, 1942. M. G. CROSBY SUPERREGENERATIVE LIMITER FiledFeb. 5, 1940 6 Sheets-Sheet 2 A AAAAA VVVVVVV lNvEN-roR MURRAY G. CROSBYATTORNEY Feb. 17, 1942. M. G. CROSBY SUPERREGENERATIVE LIMITEE FiledFeb. 5, 1940 6 Sheets-Sheet 3 lNVENTOR MURRAY G. CROSBY ATTORNEY Feb.17, 1942. M. G. CROSBY 2,273,090

SUPERREGENERATIVE LIMITER Filed Feb. 3, 1940 6 Sheets-Sheet 4 SUPERHETERODYNE RECEIVER WITH PHASE 0R FREQUENCY MODULA- T/ON DETECT/ON SYSTEM /MEDELA Y NETWORK lNvENToR MURRAY G. ROSBY ATTORNEY Feb. 17, 1942. M. G.CROSBY 2,273,090

SUPERREGENERATIVE LIMITER Filed Feb. 3, 1940 6 Sheets-Sheet 5 y Zag 5a.s/GNAL 0N I @m2/f' l @4L/ DH l H 'Wm wut win wm lNvENToR MURRAY G.CROSBY ATTORNEY Feb. 17, 1942. M. G. CROSBY SUPERREGENERATIVE LIMITERFiled Feb. 5, 1940 6 Sheets-Sheet 6 INVENTOR MURRAY G. CROSBY /wv-f"ATTORNEY NNN WSE Patented Feb. 17, 1942 SUPERREGENERATIVE LIMITEE MurrayG. Crosby, Riverhead, N. Y., assigner to Radio Corporation of America, acorporation of Delaware Application February 3, 1940, Serial No. 317,041

(Cl. Z50-20) 17 Claims.

This application concerns use of the principle of super-regeneration toprovide a limiting effect for removing amplitude variationsfrom signalssuch as frequency and phase modulated signals or keyed signals. Severaldifferent arrangements of super-regenerative amplifiers are disclosedwhich use either the conventional super-regenerative circuits orcircuits with improvements to make them especially adapted to thefunction of limiting.

In describing my invention, reference will be made to the attacheddrawings wherein Figures 1, 2, 3, 4, and 6 each show differentmodifications of my improved frequency modulated wave arnplitudelimiting means, including super-regenerative oscillators, with means forapplying frequency modulated waves thereto, quenching means and meansfor deriving limited frequency modulated waves therefrom and utilizingthe same. illustrate the limiting action of the oscillator, whileFigures 6a, 6b, and 6c are used to illustrate the operation of themodification illustrated in Figure 6.

In the prior art of limiting circuits, the practice has been to use anamplier which was fed by a signal strong enough to load it to saturationso that a constant output is obtained regardless of the input amplitudevariations. In the usual case, however, this type of limiter has thecharacteristic that when the input is increased beyond saturation to anappreciable degree, the output of the amplifier decreases. This decreasein output is just as undesirable as an increase in output for mostlimiter uses. the expedient that is resorted to is to cascade alternatestages of amplification and limiting.

The cascade Aarrangement involves a large number of tubes with theirassociated coupling networks so that an effective limiter of this typeinvolves considerable equipment. It is the purpose of this applicationto disclose an improved limiter based on the principle ofsuper-regeneration which not only involves less equipment, but can bemade more effective than limiters known heretofore.

The theory of super-regenerative reception has been described byHikosaburo Ataka in an article entitled: On super-regeneration of anultra-short wave receiver, published in the August 1935 issue of theProceedings of the I. R. E. Further theory is described by Frederick W.Frink in an article entitled: The basic principles of super-regenerativereception, published Figures 5a, 5b, and 5c are graphs used toConsequently, J

the I. R. E. Briefly, the theory of super-regeneration is that thequench frequency stops the oscillating detector from oscillating duringone half cycle of the quench frequency and allows it to build up asustained oscillation during the other half cycle. This is shown in Fig.5a in which a square wave form quench frequency is used. With no signalapplied to the circuit, the oscillations start after a time 'I' haselapsed and continue for the time A. During the part of the quench cyclemarked D the oscillations are quenched or stopped. With signal present,the oscillations start after the time T has elapsed and continue for thetime B which is longer than the time A. In reality, this time T isshorter than the time T by virtue of the fact that the presence of thesignal increases the rate of build-up of the oscillations; however, theresultant effect upon the energy contained in the radio-frequencyoscillation is the same as though the signal merely started theoscillations at an earlier time.

From a comparison of the No signal and Signal on diagrams of Fig. 5a, itcan be seen that the difference between the radio-frequency energypresent with no signal and that present with signal is rather small inpercentage. That is, the distance A is different from the distance B bya small percentage of either distance. Consequently, when an amplitudemodulated signal is applied to this circuit, the percentage of amplitudemodulation appearing in the super-regenerated radio-frequency energywill be smaller than that existing on the applied modulated wave. Thisphenomena is relied upon to produce the limiting action in the inventionof this application. The modulated signal which it is in the January1938 issue of the Proceedings Of 55 desired to limit is applied to asuper-regenerative amplifier and the radio-frequency energy built up bythe super-regenerative effect is utllized as the limited signal. Theordinary superregenerative oscillator, used as a regenerative amplifierinstead of in the conventional manner as a detector, producesconsiderable limiting action, but the improved arrangements describedherein are capable of practically complete limiting. By the genericexpression angular velocity-modulated carrier waves" used in the claimsis meant frequency, or phase, modulated carrier waves, as distinguishedfrom amplitude modulated carrier waves.

The circuit of Fig. 1 shows how the ordinary separately-quenchedsuper-regenerative amplifier may be used as a limiter in a frequencymodulated wave receiver, such as a frequency or phase modulationreceiver. InA this circuit the signal is received on antenna I andconverted to intermediate frequency by radio-frequency arnplifying,heterodyning and demodulating means in unit 2 and intermediate-frequencyamplifiers and band-pass lters in unit 3 which contain the necessaryelements of a superheterodyne receiver. Tuned circuit 4, which iscoupled to the output of the apparatus in unit 3, is thesuper-regenerative oscillating circuit which oscillates by virtue of itsconnection in the negative transconductance circuit consisting of thescreen grid 6, coupling condenser C, suppressor grid 8 of tube The tubeI0 is operated with its plate I2 at a voltage lower than the voltageapplied to the screen grid 6 so that the well-known negative resistancecharacteristic is obtained between the suppressor grid and the screengrid. The quench oscillator I6 is coupled by transformer I8 to thecontrol grid 20 so that on the positive half cycles of the quenchoscillations, the negative resistance is present to allow oscillationsto build up in tuned circuit 4, and on the negative half cycles thecontrol grid is biased negative so that the negative resistance isabsent. This quench ocil- L lator may be either of square wave form orof sinusoidal wave form.

The radio-frequency portion of the oscillations built up in circuit 4are electron-coupled to the plate I2 of tube I0 and appear in the tunedprimary 24 of transformer 26 to be passed by the tuned secondary 28thereof to unit 30 which contains the means for converting the frequencyor phase modulation into amplitude modulation and detecting the same. ofwave length deviation may be increased by tuning the circuits 24 and 28of transformer 26 to a harmonic of the oscillations produced in circuit4 which are of the same frequency as the incoming signal. This isbecause, as disclosed more in detail in my United States Patent#2,081,577, dated May 25, 1937, and in my United States Patent#2,112,881, dated April 5, 1938, multiplication of the frequency of thewave correspondingly multiplies the modulation deviation thereof.

In the conventional use of the super-regenerative circuit, detection isaccomplished and it is the detected or audio-frequency potentials thatare utilized in the output. In the use shown here,

it will be noted that the radio-frequency oscillations that are built upare not detected within the tube, but are passed on as radio-frequencyenergy. 'I'his energy consists of pulses of osciliations which appearonce per cycle of the quench frequency. When the pulses are passedthrough a selective circuit such as a tuned circuit or a tunedtransformer, the pulsations are smoothed out so that the quenchfrequency does not appear in the output which is fed to the frequency orphase modulation converting circuits. In the circuit of Fig. 1, thetuned primary 24 and tuned secondary 28 of transformer 26 performs thisfunction which amounts to the removal of the side frequencies producedby the quench frequency.

The arrangement of Fig. 2 differs from that of Fig. l in that thelimiter is placed in the radio-frequency circuit of the receiver insteadof the intermediate-frequency circuit. The arrangement of Fig. 2 alsoutilizes the self-quenching instead of the separately-quenchedsuperregcnerative circuit. Placing the limiter in the radio-frequencyportion of the receiver has the advantage that the super-regenerativeaction If desired, the degree builds up the signal to a high 'levelearly in the receiver so that less amplification is required in thereceiver. The use of a self-quenching superregenerative circuiteliminates the necessity of the separate quench oscillator tube. In thiscircuit, the signal is received on antenna 40, induced in tuned circuit42, the latter being coupled with the grid 44 and cathode 46 ofamplifier tube 48. 'I'he amplified wave appears in the tuned circuit 54coupled with the anode 56 of tube 48. Tuned circuit 54 is thesuper-regenerative oscillating circuit coupled between the anode 58 andgrid 60 of the super-regenerative oscillator tube 62. As is conventionalwith a self-quench oscillator, a

` high value of grid leak 64 is used and positive voltage is fed fromthe plate supply through the grid leak 64 to the control grid 60 ofoscillator tube 62. The grid leak is shunted by condense; 65. Part ofthe radio-frequency energy from the oscillating circuit 54 is fedthrough coupling and blocking condenser 68 to the detector and beatingoscillator included in unit 'I0 where it is heterodyned to intermediatefrequency and passed through the band-pass intermediate-frequencyamplifier 14 to the frequency or phase modulation detecting system 16.

In the circuit of Fig. 3 a novel means is utilized to remove thevariable part of the built-up oscillations so that the degree oflimiting is mad' practically complete. By a study of Fig. 5a, it can beseen that if the first part of the operational part of the quench cyclewere removed, the radiofrequency energy would have the characteristic asshown in Fig. 5b and would have the same average value whether signalwas present or not. The circuit of Fig. 3 shows a means for quenchingoff the rst part of the built-up oscillations so that this high degreeof limiting is obtained. Signal is received on antenna 90 and fedthrough radio-frequency circuit 92 to the grid 94 and cathode 96 ofamplifier 98 which has its anode |00 coupled through condenser |02 tothe superregenerative oscillating circuit |04 connected with the grid|06, cathode |08 and anode I|0 of the oscillator tube ||2. 'I'heoscillator tube ||2 is modulated by the quench voltage from tube ||6.Tube ||6 is connected as a negative transconductance tube with its platevoltage lower than its screen voltage. The anode I|8 of tube I|6 issupplied by resistance |20 with a direct-current potential fromresistance |22 lower than the direct-current potential supplied byresistance |24 to screen grid |26. This produces a negative resistancebetween the suppressor grid |28 and screen grid |26 so that resistors I30 and |24 in conjunction with condenser |32 will form a multivibratorcircuit. The output of a multivibrator circuit is not exactly squarewave form, but I have found that with this circuit there is a limitingeffect produced by taking the output from the plate circuit whichsquares ofi' the Wave form. This square wave form voltage appearing atthe plate of tube ||6 is used as the plate voltage for tube |I2 so thattube ||2 may oscillate on the positive halves of the cycle.

Tube |36 is the heterodyne detector which has fed energy to its signalgrid |40 from the superregenerative amplier ||2, and a combination ofquench voltages and beating oscillator voltage is supplied to theinjector grid |42. The beating oscillator voltage is fed from source ofoscillations |46 through condenser and resistance coupling |46 and |50to the injector grid lead |52. The square wave form quench voltage isfed from resistor |20 through variable time delay network |64 to theinjector grid lead |62. This quench voltage is time delayed lust enoughto make detector |88 inoperative during the first part of theoperational half of the quench voltage upon which the super-regenerativeamplifier operates. That is, the quench voltage is fed to the detector|88 soas to allow .it to operate onlyafterthetime'lhaselapscdonthehalfwave of the super-regenerativeoscillator quench voltage. This rejects the portion of theradio-frequency oscillations which are dependent upon the signalamplitude so that the radio-frequency pulses which operate the detectorhave the form shown in Fig. 5b. It has been shown in the above mentionedarticles on the theory of super-regeneration that the built-uposcillations have the same frequency as the incoming Signal and willfollow frequency Aor phase variations. Consequently, this limiter willconvey the frequency or phase modulations on the wave, but will removethe amplitude variations. Intermediate frequency energy is available attransformer |68 for subsequent selection in intermediate frequencyamplifier |62 and conversion to amplitude modulation for detection inunit |64 for utilization at |66.

In the circuit of Fig. 4, the same principle is used as in the circuitof Fig. 3, but instead of quenching the subsequent heterodyne detectoror an amplifier at the proper time, a. second superregenerativeamplifier is arranged to amplify the output of the first and theirquench voltages are relatively time delayed so that the second does notstart operating until the first has operated long enough for thevariable part of the oscillation to transpire. Thus. the oscillatoroperates with a quench and radio-frequency wave as shown by Fig. 5a andthe second oscillator has them also, but they are time displaced asshown in Fig. 5c. This makes the second oscillator receive its excitingvoltage from the rst oscillator at a time after the rst oscillator hasbeen built up to full alnplitude. Since this full amplitude is constant,the signal which excites the second super-regenerative ampliiler isconstant so that its output is constant.

The two super-regenerative ampliflers in Fig. 4 consist of tubes |10 and|12 with their respective oscillating circuits |14 and |16. The tunedcircuit |14 is coupled to antenna |18 and regeneratively connected tothe anode |19, grid |80 and cathode |82 of tube |10. 'I'he anode |19 oftube |10 is coupled by condenser |84 to circuit |16. Tuned circuit |16is regeneratively connected to the anode |88, grid |90, and cathode |92of tube |12. A tuned circuit |96, connected with the anode |88, suppliesoutput to unit |98. The unit |98 includes an oscillator first detector,intermediate-frequency amplifier, phase or frequency modulated waveconverter and detector system.

Quench voltage is fed directly from the plate ||8 of square wave formgenerator tube ||6 to the screen grid 206 of the first ampliiier tube|10 and through a time delay network |54 to the screen grid 208 of tube|12.

The oscillator ||6 and its circuits including the time delay network |54in Figures 3 and 4 are substantially similar and since it has beendescribed in detail in connection with Figure 3. it will not bedescribed in detail again in connection with Figure 4.

The radio-frequency output appears in tuned circuit |96 which is in theplate circuit of the second super-regenerative amplifier |12. If deputto26o circuit |18maybetimedtoaharmonic ofthefrequencytowhichcircuit |14 istuned so that a frequency multiplication takes place to multiply phaseor frequency deviations. Likewise. and for the same purpose, circuit |88maybetuncdtoaharmonic ofthefrequency to which circuit |18 is tuned.

In the circuit of Figure 6, I show another novel means for removing thevariable portion of the built-up oscillations. A resonant circuitcomprising LI, Ci is regeneratively connected to the grids 228 and 222,anodes 224 and 226 and cathodes 228 and 288 of tubes 282 and 284,respectively.sothattheybothoscillateatthesame frequency if they areadjusted the same. However, one of the tubes. say 284. is made partiallyself-quenching as shown in the diagram of Figure 6b. The other tube 282ls merely quenched by the quenching oscillator 248 which may be eitherof square or sinusoidal wave form. This partial self-quenching isproduced by the use of a high resistance grid leak 286. Thus. in Fig. 6.tube 282 has a relatively low resistance grid leak 288 so thatself-quenching is absent and tube 284 has a high resistance grid leak286 so that as soon as the oscillations build up they are quenched bythe bias provided by the grid leak 286. 'I'he phase or frequencymodulated waves are supplied at 260 to control the operation asdescribed hereinbefore and the limited phase or frequency modulatedwaves are supplied from output inductance 250' to converting anddetecting means. This means may comprise apparatus as included in unit88 of Figure 1 where the inis taken fron a heterodyne receiver or maycomprise the apparatus included in units 18, 14 and 16 of Figure 2 whenthe input at 250 is at radio frequency.

When the waves of Figs. 6a and 6b are combined in push-pull in thecircuit C2, L2 connected to the anodes 224 and 226, the wave of Fig. 6bbucks that of 6a so that the resultant is as shown in Fig. 6c. Thus, theinitial or variable part of the oscillations is cancelled and only thenonvarying portion remains. Since this latter portion of theoscillations is independent of the signal amplitude, a constant outputis obtained which will be completely limited.

The oscillator including tube 240 may be of conventional form andinclude a tuned circuit 24| regeneratively connected with the anode 248,grid 245. and cathode 241 of tube 248.

The waves as graphically represented in Fig. 5d show how the ordinarysuper-regenerative ampliiier may be adjusted to produce a higher degreeof limiting by using a specially shaped quench wave form. By making themarking portion of the quenching wave. C', longer than the spaceportion, D', the built-up oscillations persist for a longer time. 'I'hismakes the variable portion. which varies in accordance with signalamplitude, small compared to the total duration of the oscillations inthe operational half of the quench cycle. Consequently, the percentageof amplitude modulation appearing on the radiofrequency output of thesuper-regenerative ampliiier is less than it would have been with aquench wave such as shown in Fig. 5a. In other words, (C'A') is smallercompared to C' than (C A) is compared to C. Hence, a higher degree oflimiting will be obtained.

Many means may be used to provide the quenching frequency alterations ofunequal time duration. For example, I may use a pair of trisired,tuncdode systems 800 connected between the secondary winding of transformerIl and the electrode Il, as shown in Fig. 1, to supply the said quenchfrequency instead of supplying the same directly from the source il. Todo so, the switch 302 is moved from contact l to contact 308 and thelimiter comprising the two triode system in a single envelope 300(separate tubes may be used) are operated as described in detail in myUnited States application #275.151, filed May 23, 1939.

With this circuit in order to obtain a wave form such as shown in Figure5d, the variable arm of potentiometer 808 is adjusted to the ground orlow potential end of the potentiometer so that no bias voltage isapplied to grid li of tube IIIII. 'I'he arm of potentiometer 3l! isadjusted to provide a finite positive bias voltage to grid 3M of tube300. This positive voltage on grid 3M causes the current through cathodeIIB to increase. 'I'he increase of current through resistance SIB,thereby makes the voltage of both cathodes more positive. The resultanteffect is to make the grid III) more negative so that it is closer toits cut-of! voltages. Similarly, by reversing the relative positions oi'the arms of potentiometers 300 and SI2 so that a positive voltage isapplied to grid M0, the grid III of tube 300 will become more negativeand a wave form which is the mirror image of that previously obtainedwill appear in the output. The wave fed in accordingly is altered inform in that the alterationsthereof are made of unequal length. Theamplitude is limited because a positive change on the grid Ill of tube300 effects a resultant negative change on the grid 3io. This phasereversal causes the electron system, comprising grid 310 and cathode328, to cause negative grid limiting for the positive half cycles of theinput wave. When grid 3H is swung negative, negative grid cut-ofi.limits the change in cathode current caused by the input wave. When thegrid 3M is swung positive, grid 3N is effectively swung negative untilnegative cut-off is reached.

What is claimed is:

l. Means for frequency multiplying frequency modulated carrier waveenergy comprising in combination, a super-regenerative amplifierconstructed to provide oscillations of substantially constant amplitude,means for impressing said wave energy. to be multiplied on saidamplifier, and means for deriving frequency multiplied Wave energy fromsaid amplifier.

2. Means for frequency multiplying frequency modulated carrier waveenergy comprising in combination, a super-regenerative amplifier tubehaving electrodes connected in an oscillatory circuit to produceoscillations of substantially constant amplitude, means for impressingsaid wave energy to be multiplied on said amplifier, and means forderiving frequency multiplied wave energy from said amplifier.

3. Means for frequency multiplying and simultaneously limiting theamplitude of angular velocity-modulated Wave energy comprising incombination, a super-regenerative amplifier constructed to produceoscillations of constant amplitude, means for impressing said waveenergy on said amplifier, and means for deriving wave energy ofincreased frequency limited as to amplitude from said amplifier.

4. Means for frequency multiplying and simultaneously limiting theamplitude of frequency modulated wave energy comprising in combination,a super-regenerative amplifier tube constructed and arranged to provideoscillations of constant amplitude, means for impressing said modulatedwave energy o n said amplifier, and means for deriving frequencymodulated wave energy of multiplied frequency limited as to amplitudefrom said amplifier.

5. A wave limiter comprising in combination, a` plurality ofsuper-regenerative amplifiers connected in cascade, each amplifier beingconstructed to produce oscillations of substantially constant amplitude,means for impressing angular velocity-modulated carrier energy to belimited thereon, and means for deriving limited wave energy therefrom.

6. A wave energy amplitude limiter comprising in combination, asuper-regenerative amplifier constructed to provide oscillations ofconstant amplitude, means for impressing angular velocity-modulated waveenergy to be limited thereon, a second super-regenerative amplifier,means lfor impressing wave energy from said first amplifier on saidsecond amplifier, and means for interrupting the operation of saidsecond super-regenerative amplifier during the variable part of theoscillatory period of the first super-regenerative amplifier.

7. A wave energy amplitude limiter comprising a first super-regenerativeamplifier constructed to provide oscillations of substantially constantamplitude, means for impressing angular velocity-modulated wave energyto'be limited thereon, a second super-regenerative amplifier, means forimpressing wave energy from said first amplifier on said secondamplifier, and means for relatively adjusting the quenching frequency ofsaid amplifiers so that said second regenerative amplifier isinoperative during the variable part of said first super-regenerativeoscillations.

V8. A modulated wave limiter comprising in combination, a pair ofsuper-regenerative amplifiers connected in cascade, each of saidamplifiers being constructed and arranged to provide substantiallyconstant amplitude oscillations means for impressing angularvelocity-modulated waves on the first of said cascadedsuper-regenerative amplifiers, means for quenching the oscillations ofsaid amplifiers by quenching oscillations displaced in time so that thesecond amplifier is excited only by the constant part of theoscillations of the first amplifier, and means for deriving modulatedwaves from the last of said super-regenerative amplifiers.

9. A wave energy amplitude limiter comprising a first super-regenerativeamplifier constructed to provide oscillations of substantially constantamplitude, a separate source of quenching oscillations therefor, asecond super-regenerative amplifier constructed to provide oscillationsoi substantially constant amplitude including means for quenching theoperation thereof, separate means for quenching the operation of saidfirst super-regenerative amplifier, means for impressing wave energy tobe amplitude limited on the both of said amplifiers, and means forcombining the outputs of said amplifiers in opposition. to cancel andremove the variable part of the oscillations.

10. A wave amplitude limiter comprising in combination, a firstsuper-regenerative amplifier constructed to provide substantiallyconstant amplitude oscillations, a separate source of quenchingoscillations therefor, a second superregenerative amplifier constructedto provide substantially constant amplitude oscillations including meansfor quenching the operation thereof, separate means for quenching theoperation of said first regenerative amplifier in synchronism with thequenching of said ilrst amplifier, means for impressing modulated waveenergy to be llmited on the first of said ampliers, and means forcombining the outputs of said amplifiers in opposition, to cancel andremove the variable part of the oscillations.

11. A wave energy amplitude limiter comprising in combination, asuper-regenerative ampliiier constructed and arranged to produceoscillations of substantially constant amplitude, a source ofalternating current the alternatlons of which are separated by unequaltime duration coupled with said amplifier for quenching the operationthereof, means for impressing angular velocity-modulated wave energy tobe limited on said amplifier, and means for deriving limited wave energyfrom said ampliiier.

12. In a system for limiting the amplitude of wave length modulated waveenergy and simultaneously frequency multiplying the frequency of thewave length modulated wave energy to thereby increase the degree ofmodulation and demodulating the same, an electron discharge devicehaving a plurality of electrodes, an input circuit connected between apair of said electrodes, an output circuit connected between anotherpair of said electrodes, means for coupling said electrodes andenergizing the same by directcurrent potentials whereby said tube andcircuits operate as a super-regenerative oscillator, means forimpressing Wave length modulated wave energy on said input circuit,means for deriving limited wave length modulated wave energy from saidoutput circuit, and means for tuning said output circuit to a harmonicof the frequency to which said input circuit is tuned.

13. In a wave length modulated wave limiting system, a plurality ofcoupled cascade superregenerative amplifiers including a source ofquenching oscillations, means for impressing wave length modulated waveenergy on the first of said amplifiers. means for deriving wave lengthmodulated wave energy from the last of said ampliiiers, means forapplying oscillations to said ampliers for quenching the operation ofthe same, and means for causing a delay in the application of thequenching oscillations to certain of said amplifiers.

14. In means for limiting amplitude variations on frequency modulatedcarrier wave energy, an oscillation generator of the super-regenerativetype comprising an oscillation generator tube having electrodes coupledin an oscillatory circuit, means for energizing the electrodes of saidtube to produce therein oscillations of constant amplitude, means forinterrupting said oscillations periodically, means for entraining saidoscillator with said modulated carrier wave energy.

15. In a frequency modulated carrier Wave receiver, a super-regenerativecircuit comprising an oscillator generator tube having electrodesconnected in an oscillatory circuit to produce oscillations of constantamplitude, means for quenching the oscillations of said generatorperiodically, means for impressing frequency modulated carrier waveenergy of variable amplitude on said generator to entrain the generatoroscillations.

16. In a limiter network for signals of variable frequency, anoscillation generator tube having electrodes coupled in an oscillatorycircuit, means for energizing the electrodes of said tube to producetherein oscillations of substantially constant amplitude, means forinterrupting said oscillations periodically, and means for entrainingsaid oscillator with variable frequency signals having amplitudevariations to be eliminated.

17. An amplitude limiter network, for angular velocity-modulated carrierwaves, comprising a super-regenerative amplier constructed to provideoscillations of substantially constant amplitude, means for applyingsaid waves to said arnplifier, a modulated wave transmission circuitfollowing said amplier, means for supplying modulated wave energy fromthe said ampliiier to said transmission circuit, and means forpreventing transmission through said transmission circuit during thevariable part of the oscillatory period of said super-regenerativeamplier.

MURRAY G. CROSBY.

